Re: adding 2 contacts via POST, why doesn't it work?

Looks like this is likely a problem with our documentation and the clarity of this endpoint. We don't actually allow creation of more than one contact per request. The fact that we actually create the first contact and ignore the second is probably a defect as well, we don't usually like to drop requests on the floor without appropriate error messaging back to developers. Any chance you can point out the documentation that caused this confusion, I'll make sure we update it.

Re: adding 2 contacts via POST, why doesn't it work?

Thanks, definitely a lack of clarity into that statemen that's causing the problem. That statement is really there to help lead developers to the right API for the right job. Because we only support creating a single contact per POST request, you need to do serial HTTP requests, which can add up to quite a bit of round trip time. We recommend only using this API for fewer than 25 consecutive requests for this reason. It's primary intention is for interupt driven creation requests, such as from a signup form or when updating a single contact record in a CRM. The Bulk Activity API is asynchronous and intended to be used for bulk updates or bulk adds.

In the scenario you described, it may make more sense to think about the problem in reverse. Instead of saying "these 10 contacts will be on lists a, b and c and these 12 will be on b and c", you could think of it as "22 contacts need to be on list b and" as a single Bulk Activity request and "10 contacts need to be on list a" as a second.

Sorry again for the confusion, we'll look at changing the wording to make the intention of the docs more clear.